all repos — cryptopals-challenges @ b8f9f6f24713e91c948e4acbcadad4c56021fa5c

cryptopals-challenges

set1/src/repeating-key-xor.c

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#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

/*
void repeating_key_xor_stream(uint8_t *key, size_t key_len)
{
	//
}
*/

void repeating_key_xor(const uint8_t *data, const size_t data_len,
               const uint8_t *key, const size_t key_len)
{
	uint8_t c;
	size_t i, k;

	for (i = 0; i < data_len; i = i + key_len) {
		for (k = 0; k < key_len && i+k < data_len; ++k) {
			c = data[i+k] ^ key[k];
			putchar(c);
		}
	}
}

int main()
{
	uint8_t data[] = "\x1c\x01\x11\x00\x1f\x01\x01\x00\x06\x1a\x02\x4b\x53"
	                 "\x53\x50\x09\x18\x1c\x00\x00\x00\x00\x00\x00\x00";
	uint8_t key[] = "\x68\x69\x74\x20\x74\x68\x65\x20\x62\x75\x6c\x6c\x27"
	                "\x73\x20\x65\x79\x65";

	repeating_key_xor(data, sizeof(data)-1, key, sizeof(key)-1);

	return EXIT_SUCCESS;
}